Technical Analysis
Description of Microgrid Technologies
“A microgrid is a localized group of interconnected loads and energy resources that normally operates connected to and synchronous with the traditional centralized grid (macrogrid), but can disconnect and function autonomously as physical and/or economic conditions dictate” (USDOE 2018). Breaking down the description of a microgrid from the United States Department of Energy there are two key technologies. First, is the ability to use energy generated from the microgrid parallel to the energy generated by the traditional electrical grid, or macrogrid in this case. Second, is that microgrids can operate autonomously from the macrogrid at any point in time. To understand these concepts we analyzed the specific technical details of three different types of microgrids. To assist Lafayette College with the Climate Action Plan, four different microgrid alternatives have been created to help reduce carbon emissions as well as increase energy efficiency.
“Islanding” is one of the primary technologies that form a microgrid. This is especially beneficial for emergency response, and energy security. This benefit helps with one of the larger problems that centralized grids have which is the power outages that occur during natural disasters. Having a microgrid can mitigate this issue because of its ability to operate autonomously which increases resiliency and reliability. The seamless connection between the microgrid and the macrogrid which is essential to islanding also creates the opportunity to buy and sell energy from the macrogrid.
The second primary technology is the availability to sell energy created by the microgrid back to the electric company that handles the macrogrid. The traditional macrogrid is a centralized form of energy generation that focuses on mass generation from singular power plant. “electric utilities generate all the electricity they sell using just the power plants they own” (EIA 2018) Microgrid technology decentralizes energy production from the traditional macrogrid and provides the opportunity to use different distributed energy resources on a smaller scale. “decentralized solutions [microgrids] could manage the integration of thousands or tens of thousands of distributed energy resources in a way that also maximizes reliability and resilience” (Hirsch)
Analyzing the advantages and disadvantages of microgrids and traditional macrogrids offers insight on how microgrids are beneficial and complements the current macrogrid technology.. Macrogrids are centralized generators, usually power plants, that create massive amounts of energy to be distributed to the public. “In industrialized countries, microgrids must be discussed in the context of a mature “macrogrid” that features gigawatt-scale generating units, thousands or even hundreds of thousands of miles of high voltage transmission lines, minimal energy storage, and carbon-based fossil fuels as a primary energy source” (Hirsch 2018). This technology offers easy access to electricity for mass consumption. Because a macrogrid creates such a large amount of electricity for a large number of people there are two major drawbacks. One is the possibility of a blackout which is a risk to energy security. A large blackout in a major city or area can cause numerous amounts of problems, from a simple inconvenience to temporary shutdowns of businesses. The second drawback is the sizeable amount of CO2 emissions. The issues of energy security and CO2 emissions can be mitigated with the implementation of microgrids. The first mitigation aspect is the “islanding capabilities that microgrids have. This islanding capability enhances energy security especially in times of crisis and natural disasters. The second mitigation aspect is the microgrids ability to use renewable energy resources. Microgrids make it possible for institutions and residential areas be powered mostly by renewable energy. An example of this is at the University of California San Diego. The microgrid at UCSD is used to “supply 85% of campus electricity needs, 95% of its heating, and 95% of its cooling.” (Berkeley Labs 2018). These advantages that come with microgrids will help distinguish itself from the traditional macrogrid. But, there are some obstacles that come with this new technology
One of the obstacles of microgrids is that they do not create massive amounts of energy unlike the traditional electrical grid. Another obstacle that is specifically for microgrids that use renewable energy generation is the variability in energy production. Solar for example, can only generate energy during the day. The way that this obstacle can be overcome is the use of energy storage. Energy generated during the day from solar PV cells can be stored for nighttime usage with proper energy storage. These obstacles can vary in magnitude depending on the type of energy generation and storage. To make sure the Lafayette is ready to implement microgrid technology we have analyzed the different types of energy generation and storage that are compatible with microgrids.
An academic journal published by Hirsch, Guerro, and Parag titled “Renewable and Sustainable Energy Reviews” provided us with a list of different types of energy generation and storage along with their respective advantages and disadvantages. The main types of generation for microgrids are microturbines, fuel cells, and renewable generation for example solar photovoltaic cells (Hirsch, 2018). Microturbines are usually small combustion turbines that have the ability to generate heat and electricity on a small scale. The advantages of microturbines are that they are dispatchable which describes the ability of a generator that can be turned on or off at the demand of the user. Microturbines also produce low emissions, have multiple fuel options, and is CHP capable. A disadvantage is that microturbines still produces some greenhouse gas emissions. Because of this if Lafayette were to use a microgrid with a microturbine the campus would not be able to become carbon neutral. To get a sense of scale in regard to emissions The U.S Department of Energy compared different types of energy generation and their respective emissions. “Emissions [for microturbines] range from 667 to 804 lbs/MWh. For comparison, a typical natural gas combined cycle power plant will have emissions of 800-900 lbs/MWh, and a coal plant will have CO2 emissions near 2,000 lbs/MWh” (USDOE 2016). Microturbines also produce energy on a relatively small scale.
Fuel cells have the ability to convert chemical energy into electrical energy that can be used in a microgrid. The advantages of fuel cells are that they are dispatchable, they have zero on site pollution, and are CHP capable. The disadvantages are that fuel cells are relatively expensive and have a limited lifetime.
The next main source of energy generation is renewable generation. The primary sources of renewable energy generation are solar photovoltaic cells, wind turbines, and hydroelectric. The general advantages of using renewable generation are that they have zero fuel cost and have zero emissions. The disadvantages are that renewable generation is not dispatchable without storage and the energy production is variable and not controllable. In regard to microgrids it is not possible to integrate these options without the ability to store the generated energy, especially for renewable energy. (Hirsch 2018).
After generation microgrids need a main storage unit to store the excess energy generated. The main types of storage units include batteries, regenerative fuel cells, and kinetic energy storage. (Hirsch 2018). The first main type of storage for microgrids are batteries which have a long history of research and development which should make it easy to implement into a microgrid but there are some disadvantages. There are two main issues that regard batteries, one is that they have a limited number of charge and discharge cycles meaning that after a certain amount of usage batteries wear out and are not as efficient. Second is the issue of waste disposal that comes with disposing the efficient batteries.
The next storage option are regenerative fuel cell which are the opposite of a fuel cell in that it stores energy instead of produces it. The unique benefit of this type of storage is that it has the ability to support continuous operation at maximum load without the risk of damage. Regenerative fuel cells are also a clean way to store the generated energy. The disadvantages are that they have a limited discharge time.
The last method discussed in this study is a flywheel a type of kinetic energy storage. A flywheel is a heavy revolving wheel that takes the energy that was generated and stored by a very high-speed rotor which keeps the energy as rotational energy (Energy Storage Association 2018). The advantages of this type of storage is that is very responsive, has a high charge-discharge cycles, and high efficiency. The disadvantages are that flywheels have high standing loses if the technology is not implemented properly (Hirsch, 2018).
The Three Types of Microgrids
There are three levels of microgrid energy production: emergency generation, demand response, and optimization (Hirsch, 2018). In an emergency generation microgrid the electrical generation is only activated in the event of a macrogrid power outage. The microgrids primary use is to support energy usage for critical facilities in the event of a natural disaster or other type of power outage. This emergency generation focused microgrid provides greater energy security and is not economical beneficial until the system becomes more complex. The next type of microgrid is one that focuses on a demand response system that would supply energy constantly. The demand response method involves either buying energy from the macrogrid or selling energy to the macrogrid. If the demand for energy exceeds its supply then the microgrid can buy power directly from the macrogrid. If the energy supply exceeds demand than the microgrid can sell energy back to the macrogrid for energy credits. If a demand response system was comprised of renewable generation, the college would decrease its currently CO2 emissions, but would still be responsible for CO2 from the energy supplied from UGI (Ferretti, 2018). In an optimized microgrid, the controller is highly advanced in that it analyzes the usage of energy based on cost. The microgrid controller can find the cheapest source of power to use at any given time. The price of electricity fluctuates during different times of the day due to demand. The optimized microgrid can analyze the cost of energy from the macrogrid and from the microgrid and choose which type of energy to use. If Lafayette invested in a renewable island microgrid, the school would become completely carbon neutral, and even offset some of the carbon from the city if it was to sell excess energy back to the macrogrid (Ferretti, 2018). At Lafayette it would likely be more feasible to either implement an emergency response system or a demand response system, as it would be a considerable investment for Lafayette to implement an optimized microgrid.
Four different microgrid options (Kirby/Metzgar/Anderson)
(Introduction, stating what would zero emissions look like from an energy creation standpoint, where it would go, what options the college has…)
Our group identified four alternatives to see if Lafayette can utilize a microgrid in any capacity. We focused our research on these four microgrid alternatives because they each demonstrate a different purpose or usage for the college. The first option utilizes on campus space to create power for a just some basic functions of the building the power is implemented on. The second option is another on campus microgrid that enables more microgrid characteristics, such as the option for islanding, or disconnecting from the grid while maintaining power or critical functions. The third option is an off campus option that resembles a full microgrid, being able to island as well as being able to net meter, for the off campus location alone. The last alternative is off campus as well, but instead of being able to be energy independent only from Lafayette, it would supply all of Lafayette’s power needs, effectively offsetting all of Lafayette emissions.
We have decided to use the following criteria to analyze the alternatives from a technical perspective: distribution, spatial requirements, power generation options, three levels of microgrids, proximity to usage, accessibility to power or energy infrastructure, and geographical. Energy storage was not included as a factor in order to narrow the scope of our research. Distribution refers to how the power created will be appropriated across campus. At Lafayette this includes the steam heating system used to heat buildings on campus, as well as the current electrical infrastructure. Space, or spatial requirements, refers to the actual amount of space that an alternative would require. Power generation options entails how the energy used for powering Lafayette would be obtained, whether it was solar, biofuels, or other alternative energies. The three different types of microgrids assess which degree of microgrid would be used and what level of power usage the microgrid would cover. Accessibility to power is how easily the alternative can access a specific power option. At Lafayette, this is an assessment of the ability of the school to acquire the means to generate power. For instance a combined heat and power system running on natural gas would be reliant on the school being able to attain and store natural gas. The geographical evaluates how the microgrid would be impacted by specific uncontrollable environmental or locational elements. This can be whether or not the sun is out, or how far from campus the alternative would be.
Lafayette’s campus has very few optimal spaces to set up energy creation, for example, Kirby Sports Center has two and a half acres of roof space that could be turned into solar. In comparison to the total amount of solar needed to offset campus fully, two and a half acres is not enough. The campus would need the capacity for five megawatt hours (5 MWH) at any given time (Ferretti, 2018). This means that the college cannot simply have the ability to power 5 MWH but to continuously do so for continuous operation of critical campus processes. The equivalent of a constant 5 MWH is close to 100 acres of solar panels (Ferretti, 2018). This leaves the only option for space for a full campus microgrid powered by solar alone to be out at Metzgar Fields, where there are closer to 200 acres of accessible land. A private farmer uses 90 acres of it, Lafayette would have to let this tenant go in order to utilize the most feasible land and not disrupt the airport’s activities. There is another option Lafayette can pursue which is less spatially intensive, combined heat and power. Combined heat and power (CHP) systems utilize a normal power plant, but make the excess heat created turn into a heating source for the school, increasing the overall efficiency of the process.
Kirby For Campus
This microgrid alternative utilizes solar power on the rooftop in order to power critical functions in Kirby, but cannot power the whole building. Kirby sports center has two and a half acres of accessible roof space, and is the single largest source of energy consumption on campus at close to 10% of the total consumption (Fechik-Kirk & DeSalvo, 2018). Reducing consumption by adding solar and giving it the option to island and produce energy independently would reduce the College’s energy bill as well as lead the way towards further implementation on campus in the future. Although two and a half acres would not be enough to fully supply Kirby, it would allow Kirby to operate some of its critical processes such as lighting and heating in crisis situations, giving the Lafayette community as well as potentially the surrounding Easton community a shelter to use in times of crisis. Using Kirby as a potential hub for green energy would create a microgrid on the second, being able to handle emergencies mainly but also using solar would allow for a return on investment with selling the energy to the grid (Ferretti, 2018).
The Kirby microgrid alternative in terms of distribution of power would be straight forward. The power generated would be on Kirby, and can connect to the relatively new existing infrastructure. Spatially, Kirby does not offer substantial room for solar to work optimally, since it would only be powering a limited amount of Kirby processes. Solar as a power source for Kirby is feasible with the roof space Kirby provides, and is the best rooftop on campus for solar implementation. With regards to other power generation options, solar is still the best, but in order to cover all of Kirby’s power needs, another source would be needed. This other source could be a CHP plant, or biofuel generators, to remain in line with Lafayette’s CAP. Using the solar would be able to maintain the first level of a microgrid, covering critical building operations such as heat or plumbing or some electrical as well as help alleviate energy costs. Proximity to usage would be in direct proximity, since the application of the microgrid and the power source are on the same building=. With the next metric, accessibility to power, there is another item to consider, whether or not Kirby is heated by steam or not, or has its own boilers. Kirby has been recently renovated and has a modern power infrastructure as well as being close to Lafayette’s power station down the hill. Geographical criteria for Kirby will not impede on microgrid implementation with solar as the power source. There are no trees blocking roof coverage, so weather factors are the only worry, and the average amount of peak sunlight per day is between three and four hours.(Baker 2018)
Anderson courtyard
On campus, if the spatial factor was not sufficient, for example if the solar field did not have room and there was no way of adding room, then there are some other options like CHP, or combined heat and power. Combined heat and power has potential because of the current infrastructure in place across campus. On the hill, a central heating station boils water and turns it into steam. This steam is then sent through pipes all across campus heat campus buildings. Since there is already a current steam heating infrastructure on campus, combined heat and power may be more efficiently put to use than other alternatives like generators or even the equivalent power generation in solar (Ferretti 2018, Hayes 2018). Currently Lafayette brings in natural gas through pipes coming from a larger natural gas grid owned by UGI (Ferretti , Hayes). The change would be adding a power plant to this station to heat the water instead of just heating alone.
Multiple options for fueling a CHP plant for the microgrid fit within the guidelines of the Climate Action Plan as well, like biofuels. There is another group of Engineering Studies students researching biofuels. In the recent 2018 Lafayette Climate Action Plan over 20 alternatives for reducing emissions and reaching carbon neutrality were looked at. Microgrids as well as a biofuel power plant were amongst them. Biofuels encompass a wide range of fuel options as long as they come from renewable sources, such as vegetable oil, or wood chips or such (Wallace 2010) and Ferretti. In discussions with the director of facility operations a few that were brought up were vegetable oils and a newer biofuel called wood oil (Wallace 2010). This is what’s used to turn water into steam for heating. What would be needed for a CHP system is an on-campus power plant with storage capacity as well as an energy source. Looking at these biofuels can shed light on what green/renewable energy source can be used most efficiently. Current problems with things like wood oil are its availability to Lafayette. The manufacturer of it is in Canada, so supply issues could arise in the future and that puts energy security availability into question. Storage of a sufficient amount is also an issue, the college currently has capacity for 50,000 gallons of whatever fuel would be needed, but for wood oil, with a PH of 12, there may be some changes needed (Ferretti, 2018). Using a microgrid based off of CHP would still be a very powerful and efficient option but to discuss using a CHP plant in the context of a microgrid, all of what goes into a CHP needs to be taken into account as well.
It is worth noting that when Mr. Ferretti, director of operations, made the CHP system proposal for Lafayette in the past, UGI was unable to follow through with it because of the current external infrastructure in place (Ferretti , Hayes). The pipes that supply the natural gas to the school for heating the steam heating plant were too small for the load required for a campus CHP system based off of natural gas to be feasible (Hayes, 2018). Natural gas as part of the Climate Action Plan discussion may not be a ‘green’ energy, but it does offer a reduced carbon footprint, and when used for a CHP system, does so even more by increasing the efficiency of the energy creation. Creating a CHP system for the entirety of campus would be a large undertaking, especially if it were to comply with the Climate Action Plan.
A more viable alternative is creating a localized CHP plant for Anderson Courtyard, or, to be able to power Lafayette enough to displace Anderson Courtyard’s energy usage as well as provide heat to buildings. This would allow the College to not expend excessively into one alternative, as well as allow CHP to be used on campus. Stonehouse Consulting Group is looking into viable CHP alternatives and currently there are two they are looking into (Hayes, 2018). The first is one based around steam heating using microturbines (Hayes, 2018). The second is one based around liquid heating, using reciprocating engines (Hayes, 2018). The current infrastructure in place uses steam heating, but the more efficient option is the one involving liquid, and this option also has a cheaper upfront cost associated with it (Hayes, 2018). A system like this would be able to power close to 1500 KWh, compared to campus’s total energy usage of around 6000 KWh. CHP as an alternative in the Lafayette microgrid would play a large role in contributing to distributed energy resources playing into the whole system, as well as be able to heat buildings on campus so that students stay warm even in crisis situations.
Metzgar for Campus
Another alternative that was looked at was using the ample space out at Metzgar Athletic Fields and the private farming fields as solar array space to power campus. Looking at the total power production, Lafayette would need 90 acres of solar (Ferretti, 2018). There is ample space out at Metzgar to install this much, and this would allow Lafayette to stay powered indeterminately and during peak power usage during the summer. Room is not an issue regarding where the panels could go, but the distance became an issue for net metering, as well as playing into a true microgrid (Hayes, 27). Lafayette is 2.1 miles off of campus, and UGI has a policy that no net metering can happen if the source is outside of 2 miles from the power production site (UGI, 2018). Also, in order for the microgrid to work, a direct connection needs to be established between the energy source and the campus. This makes solar power at Metzgar only able to displace what energy is used at Lafayette if Lafayette was able to net meter further than 2 miles. If Lafayette were to acquire property closer to Metzgar Fields to get into the two mile zone, then net metering would work (Ferretti, 2018). The only way this would be able to be part of a microgrid is if Lafayette installed direct lines to Metzgar fields. The implications of this could have impacts on the surrounding Easton and Forks Township community commuters in the area.
Metzgar for Metzgar
The last feasible alternative is installing a microgrid at Metzgar fields to for the Metzgar complex alone. This idea specifically power the Metzgar sports complex came from the issues that arose from the Metzgar for campus alternative. Similarly to the the Metzgar for campus microgrid, the main source of power will be from a multitude of solar arrays. The difference of this alternative is that the amount of solar PV panels needed to power the complex will be significantly lower than the previous alternative. During the periods of low energy usage at the sports complex, Lafayette College has the opportunity to sell excess energy back to UGI, the utility, with net metering. The advantage of using net metering is that Lafayette can offset their energy costs with the renewable energy sold to UGI. This alternative is the most flexible of the four because Lafayette college can decide how many solar arrays to install at metzgar to not only power the complex but to offset the campuses energy costs. While the energy used to power the campus would not be renewable if there were more arrays in this alternative, the college would still be offsetting its carbon footprint by providing renewable energy UGI.
The Metzgar for Metzgar microgrid is the most feasible alternative because of its lower upfront costs compared to, for example, Anderson Courtyard. This microgrid would fall under the second level of efficiency. It would be fully self sufficient, and be able to net meter, or use demand response. Installing a solar array out at at Metzgar would be more intensive than installing solar on Kirby’s roof because it would be close to a quarter mile or more away from the facility, so there would be some infrastructure additions besides the microgrid controller. With existing power infrastructure metric, the array would connect to what is currently in place. These additions would be purely for the ability to connect solar arrays to Metzgar and to the power grid. With regards to the distribution metric, the power generated would stay at Metzgar, so it would not be distributed far or to many buildings. In addition to energy creation, energy storage would be needed as well,. Although this was not a metric that was investigated this is an important part to how Metzgar would maintain power if disconnected from the grid. Accessibility to power infrastructure would be no big deal, Metzgar is located on Sullivan Trail, which is a large road that connects Forks Township to Easton, so connecting to the power grid will not be a large project. Solar power is environmentally friendly if looking at power generation, and has little to no emissions over a typical life cycle (UCUSA 2010).